<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1.0"/>
    <title>图片</title>
<style>
img{
    width:100%;
    height:auto;
}
</style>
</head>
<body>
<img src="xi.jpg">
<p>可以调整浏览器窗口，查看图片是如何扩展的。</p>
</body>
</html>